The present invention relates to instruments for carrying out dental procedures, and more specifically to carrying out such procedures using a high pressure liquid jet.
It is known in the prior art and in common dental practice to carry out most treatments using mechanical techniques. For example, in endodontics, which often involves many root canal procedures, a diseased tooth is first diagnosed, and then an opening is drilled through the crown of the tooth into the pulp chamber thereof. After the tooth is isolated and the field sterilized, the pulp, consisting primarily of blood-rich tissue and nerve fiber and necrotic components, is then aspirated. There remains within the pulp chamber the primary nerve fibers and blood vessels that sustain the tooth. These tissues extend from extremely fine openings in the apex of the root(s) of the tooth through a narrow channel(s), and cannot be removed solely by aspiration.
Typically, a file is then inserted into the narrow channel(s) to displace and abrade the nerve and blood vessel tissue. Increasingly larger files are inserted, whereby the narrow channel(s) is cleared of all soft tissue. After cleaning and preparation, the pulp chamber and root channel(s) are filled with a sterile solid material, and the drilled opening is filled with standard gold, silver, or other dental filling preparations.
This typical procedure is labor-intensive, resulting in a high cost factor for the dentist""s time as well as skill and experience. Moreover, the procedure may be painful, and sufficient local anesthetic must be injected to completely numb the area of the tooth for the relatively long time that the procedure requires.
Complications known to result from a root canal procedure may include infection arising from incomplete removal of the diseased tissue within the canal and pulp chamber, or the introduction of other infectious bacteria into those spaces during the procedure. In addition, the dentist may inadvertently perforate the tooth; e.g., by driving a file instrument through the apical opening at the base of the root, and the opening thus formed may provide a vector for renewed infection and inflammation. Not infrequently, drug therapy including a strong antibiotic is prescribed after the procedure to forestall these complications. Other complications include broken instruments lodged in the tooth, or fracture of the root or body of the tooth.
Recent innovations in this dental procedure include the use of laser light delivered into the pulp chamber and root channel by an optical fiber. The high power optical energy vaporizes the pulp and nerve tissue, and is inherently sterilizing. However, the products of tissue combustion may contaminate the interior of the chamber and root channel, and the laser pulses may not contact all of the tissue in the narrow root channel, causing very unsatisfactory results. To avoid these results, there is a tendency to apply an excess of laser energy, which may overheat the tooth and surrounding tissue and cause necrosis. In addition, laser energy impacting on pre-existing metallic fillings may cause dangerous reflected beams and unforeseen damage, as well as vaporized heavy metal compounds, which may be toxic.
As another example, in periodontal practice, which typically includes gingivectomy procedures, the gingiva are usually resected using a scalpel, and scaling and root planing are accomplished with specialized steel tools. These procedures and most other dental procedures are executed with mechanical drills, burrs, and cutting wheels.
Innovations such as ultrasound-driven scaling instruments, high power lasers for caries removal, and the like have not substantially altered the reliance of the dental profession on the same mechanical tools that have been in use for almost a century. All such mechanical tools generate high levels of vibration and sound that are directly conducted through bone to the ears of the patient, resulting in patient comfort problems. Also, the mechanical tools, as well as ultrasound tools, generate substantial amounts of heat in very localized areas, causing direct pain stimulation. Water spray devices are provided to remove this heat, but may not be effective at the point source of the heat. In this regard, the heat generated by dental lasers may pose the greatest problem.
Clearly the prior art shows an unmet need for improved dental instruments that can carry out a wide range of dental treatment procedures without generating heat, noise, and vibration as they operate on the patient""s teeth.
The present invention generally comprises an apparatus and methods for dental treatments that overcome the problems associated with current mechanical and dental techniques and instruments. In one aspect, the invention comprises a technique for removing the soft tissue from within a human or animal tooth, whereby infectious, inflamed and necrotic tissue may be removed and the tooth and periodontal structures restored to a healthy condition. A salient aspect of the invention is that the invention obviates the need for files and other mechanically abrasive displacement tools, employing instead a high pressure jet of water or other liquid directed at the soft tissue within the tooth to excise, emulsify and aspirate the soft tissue. The soft tissue may comprise the pulp, nerve tissue and blood vessels that extend from the surrounding jaw bone through the apex of each tooth root into the root channel and to the pulp chamber of the tooth.
The invention provides a high velocity liquid jet dental tool having a handpiece and a cannula extending therefrom. The cannula is connected to a source of high pressure water or other liquid, and includes a distal orifice to deliver a high velocity jet. The pressure range of the high pressure source is approximately 500-60,000 psi, and the jet orifice is approximately 10-800 microns in diameter. The cannula may also provide aspiration to remove the fluid and tissue from the target, or aspiration may be provided by a second cannula connected to a vacuum aspiration unit. An exemplary device is described in U.S. Pat. No. 5,562,692.
To initiate a treatment method of the invention, a tooth that is diagnosed as diseased and in need of a pulpectomy/root canal procedure is opened; that is, a hole is made in the crown of the tooth using a standard dental grinding or drilling instrument. The tooth is then isolated using a dental dam or similar protective shield.
The cannula of the high velocity liquid jet tool is then directed through the newly formed hole in the crown of the tooth, and a jet of liquid is directed at the pulp and nerve and vascular tissue within the interior chamber of the tooth. The fluid may comprise medical-grade saline solution, and/or a disinfectant solution and/or an antibiotic solution and/or an abrasive solution. In the pressure range and jet diameter formed by the high velocity liquid jet tool, all the soft tissue within the tooth is cut, excised, emulsified, and aspirated out of the tooth. Aspiration may be provided by the high velocity liquid jet tool, or by the cannula of a standard dental aspiration device.
A salient aspect of the method of the invention is that the high velocity liquid jet easily removes all the soft tissue within the tooth, but is limited in its ability to cut or erode the hard calcified tooth tissue. Likewise, the jet lacks the velocity to cut through the apical root openings through which the nerve fibers and blood vessels enter the root channels from the surrounding jaw tissue. As a result, this process of pulpectomy/root canal progresses to a self-limiting extent and for example, cannot pierce the apical openings if they are naturally closed, whereby a source or complications known to result from prior art procedures. In addition, the use of antiseptic or antibiotic solutions reduce the possibility of post-procedure infection if the apical openings where to be damaged.
Moreover, the time required to excise, emulsify, and aspirate all the soft tissue within a typical molar is on the order of 10-240 seconds, so that far less time and labor is expended in the procedure. This reduction in time to complete the removal step reduces the need for local anesthesia, reduces the time that the patient may experience pain (if any), and overall increases throughput in a dental practice.
The interior chamber of the tooth is then completely aspirated and verified for completion of removal of all soft tissue. The interior chamber is then packed with an appropriate filler material known in the prior art, and the opening in the top of the tooth is filled or provided with a prosthetic crown, as is known in the dental art.
It should be noted that the fluid jet may comprise a pulsed jet formed by a pulse intensifier device in the handpiece of the dental high velocity liquid jet tool, as described in the US patent to Bair referenced above. Alternatively, the handpiece may be connected to a source of high pressure fluid to form a steady stream jet emanating from the orifice. The handpiece may be directed at other surfaces and structures to carry out endodontal, periodontic, surgical, and restorative procedures such as gingivectomy, removal of granulation tissue, muco-osseous surgery, caries removal, scaling and removal of plaque and calculus, and extractions and tissue incisions.